A navigation system performs travel guidance for enabling a user to easily and quickly reach the selected destination. A typical example is a vehicle navigation system where a vehicle is equipped with a navigation function to guide a driver to a destination through a calculated route. Such a navigation system detects the position of the user's vehicle, and reads out map data pertaining to an area at the current vehicle position from a data storage medium, for example, a CD-ROM, a DVD, or a hard disc. Typically, the navigation system displays a map image on a monitor screen to guide the user to a destination.
FIGS. 1A-1H show an example of overall procedure and screen display involved in the navigation system for route guidance to a destination. FIG. 1A shows an example of locator map screen of the navigation system when the destination is not specified. Typically, the navigation system displays a street on which the vehicle (current vehicle position VP) is running on a map image and a name of the street. Other information such as a north pointer NP, a map scale and a current time may also be illustrated on the display screen.
An example of process for specifying a destination in the navigation system through a Point of Interest (POI) search method is shown in FIG. 1B-1F. FIG. 1B show a “Find Destination by” screen for specifying an input method for selecting the destination. The “Find Destination By” screen lists various methods for selecting the destination including “Address” for specifying the city and address of the destination, “Intersection” for specifying the names of two streets which intersect with one another, and “Point of Interest (POI)” for selecting the programmed destination based on the name, category or telephone number.
When selecting, the “Point of Interest” method in FIG. 1B, the navigation system displays selection methods of point of interest (POI) either by “Place Name” or “Place Type” in FIG. 1C. The “Place Name” is to specify a name of the intended POI, and the “Place Type” is to specify a category of the intended POI. If the “Place Name” is selected in FIG. 1C, the navigation system displays a keyboard screen so that the user inputs the desired POI name as shown in FIG. 1D.
In FIG. 1E, as the user enters characters of a place name or specifies a particular place type, the navigation system narrows down the candidate place name by searching a map database. FIG. 1F shows a screen where the candidate POI name is displayed thereon as a result of the user's input. In FIG. 1G, when the user confirms that the candidate POI is a desired place to go, the navigation calculates an appropriate route to the destination. After determining the calculated route to the destination, the navigation system starts the route guidance operation as shown in FIG. 1H.
As in the foregoing example, typically, the information concerning the intended destination is stored in the data storage medium of the navigation system. However, there arises a case where an address, a place name or other information on a particular location is not found in the map database in the data storage medium. For example, when a new shop or a new restaurant is started or a road name is changed, etc., the map database of the user's navigation system may not include the data on the new shop, restaurant or the new road name because the map database may not be updated so frequently.
Such a condition is explained with reference to FIG. 2 which shows a map image in which a current position of a user's vehicle is indicated by a reference number 13. It is assumed that a location 11 is a place where the user wants to go, i.e., an intended destination, although the map database does not include address data for the location 11. Several roads are shown on the map image that are indicated by reference numerals 21, 23, 25, 27 and 29.
Since the navigation system cannot recognize the user's destination, it simply draws a line from the current vehicle position 13 to the location 11 as shown in FIG. 2. This may happen when the user specifies the location 11 on the map image which is not in the map database of the navigation system because it is a new road, new house, etc. Since the navigation system is unable to calculate a route to the intended destination 11, it is unable to perform the route guidance operation either.
In a navigation system, it is necessary to specify an address by inputting a street number (house number) and a street name to pin-point the destination. Thus, in the situation described above, the user will not only fail to arrive at the destination, but also will fail to approach a location proximate to the destination. In the situation of FIG. 2, it would be helpful for the user if a navigation system is able to guide the user to a location close to the intended destination.
Thus, there is a need of a new method and apparatus for a navigation system which is capable of assisting the user to arrive at a location proximate to the intended destination when an address of the intended destination is unavailable in the map database.